i filled it twice today to see what it woudl be at diff levels. first time i fill it i got 7.7 L/100 km not sure what that is in MPG, but the i drove only 100 km and filled it and got 8.7L/ 100 km, this is alot better the the 4 i was getting, but does it change so much from the different driving style? i don't think its cuz of that because i'm always on the highway doing about 110. theres no city driving on either tank? why the change?